The present invention relates to an apparatus for the control of at least one safety-relevant function of a machine having a machine control for the control of the movement of the machine, having at least one sensor for the sensing of an object inside a monitored zone and having an evaluation unit for the setting of a danger zone and for the triggering of the safety-relevant function on the intrusion of the sensed object into the danger zone. The invention is furthermore directed to a method for using an apparatus of this type.
An apparatus and a method of this type are known from DE 101 52 543 A2. In accordance with this reference, a safety-relevant function of a machine is triggered when an object sensed by the sensor intrudes into the danger zone of a machine. The danger zone can be fixed dynamically in dependence on the position, on the speed of movement and/or on the direction of movement of the person. The machine can furthermore also be monitored in a corresponding manner via the sensor.
While this apparatus has generally proven itself, very fast movements of the machine can in particular result in problems. Before the evaluation unit can transmit a possibly necessary stop signal to the machine control in this case, the sensor must first measure the position and possibly also the speed of the machine and transmit these data to the evaluation unit. The time the sensor needs for the measurement has the result with the known apparatus that, at high machine speeds, the danger zone must be dimensioned very generously to ensure sufficient safety for the object. A further disadvantage of the known apparatus is that the machine has to be recognized error-free by the sensor to be able to ensure the required safety since the setting of the danger zone takes place in dependence on the machine data sensed by the sensor.